1. Field of the Invention
The present invention relates generally to airplanes and more particularly to reducing electro-magnetic effects to structural components in an airplane in addition to reducing the number of steps needed to assemble components.
2. Description of the Related Art
Lightning strikes occasionally occur on an aircraft traveling near or through a thunderstorm. A lightning strike on an aircraft normally does not damage the aircraft, but may leave a burn mark. Additionally, pits or burns on the skin of the aircraft occur at points of entry or exit for the lightning strike. In particular, an electric strike arcing may occur between a fastener and a hole bore in a structure in which fasteners are used to hold different structural components of the aircraft together. The arcing may induce a defect on the surface, which induces a stress concentration. This defect is also referred to as “pitting”. Various parts of the aircraft may be more sensitive to this type of defect than others. For example, the side-of-body chord used to attach a wing to the aircraft is often made of titanium. Holes are formed in the side-of-body chord to receive fasteners to attach the wing. This type of metal is very notch sensitive.
As a result, pitting on a hole surface in a chord made of titanium greatly reduces the fatigue resistance of this part. This component and other components for the side body joint are part of a safety of flight joint and cannot have these types of defects.
One current approach to reduce electro-magnetic effects (EMEs), such as those from lightning strikes, is to use interference fit fasteners. However, with the currently used assembly processes, interference fit fasteners are hard to use because of space constraints present when installing the fasteners while attaching a wing to a body of an aircraft. Redesigning the joint is expensive and not feasible.
Current assembly processes employ “One-Up Assembly” in which once parts are put together, the different parts are not taken apart again. The complexity with the number of different fasteners makes it almost impossible to correctly realign parts if parts have to be removed once they have been put together in the assembly process. For this reason, “One-Up Assembly” is often used. For example, in attaching a wing to a body of an aircraft, several thousand fasteners may be required to attach the wing to the body. Realigning this number of holes for fasteners is very time consuming if the parts are taken apart after holes are created for fasteners to remove defects that occur from creating the holes for the fasteners. In most cases realignment is impossible if disassembly occurs.
Therefore, it would be advantageous to have an improved method and apparatus for assembling components.